HV Battery Shut Off

Rob Healy

Rob Healy

Established Member
Joined
Jun 9, 2021
Messages
70
Reaction score
24
Points
20
Location
Romford, UK
Driving
MG5
Typically, on the day I really needed to go out and do things, I got into the car and it wouldn’t go! I kept getting ’HV battery shut off’ on the screen whether I was in Auto or Electric mode.

Looking at the 12 volt battery meter, it is red and well below 12v. I’ve no idea why.
I last used the car on Sunday and it’s been in my driveway since.

Fortuitously, when the car was serviced last month, I was given AA MG cover for a year which includes home start. I’ve given them a call and they’re on their way.
 
You need to see what the HV battery status is as it’s been sat until today. If the HV battery is good then it’s not charging the 12v battery for some reason. You could put the car on charge to see if that puts charge into the 12v battery
 
Flat 12 volt battery is very likely to be the issue here !.
AA man will jump it from a pack and get you up and running in no time !.
Then check if the 12 volt is receiving a charge from the HV pack.
He maybe be able to perform a “Drop Test” on your 12 volt battery while there, ask him !.
Battery could have failed completely, not that uncommon.
Please consider buying a small jump pack ( battery booster ) in the future.
Absolute “ Must Have” piece of kit in my opinion !.
 
I’ve had the AA out and they’ve towed the car to MG because they couldn’t start it, and the diagnostic computer says there’s a chassis communication fault.
Now I’ve got to wait until MG can look at the car as they’re chock full for at least 2 weeks.
 
Lovemyev said:
I am a little surprised that they diag machine would talk to the car ?.
Did they try another 12 volt battery on the car do you know ?.
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Not that I’m aware. They were with the car for nearly an hour trying different things. Luckily, I was at home otherwise I’d have had more troubles.
 
Sorry I do not think that’s good enough to have wait two weeks for a diagnosis which could be done at the end of the day if jobs finish early. I am sure they are not working from 8.30 to 5pm. You have spent a lot of money with them ok to fix it you may have wait to get time in the work shop. Make some noise to get a diagnosis.
 
Jto said:
Sorry I do not think that’s good enough to have wait two weeks for a diagnosis which could be done at the end of the day if jobs finish early. I am sure they are not working from 8.30 to 5pm. You have spent a lot of money with them ok to fix it you may have wait to get time in the work shop. Make some noise to get a diagnosis.
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I totally agree !.
Come on folks, it takes 5 minutes to plug in the diag and then let it do it's thing while you do something else !.
I think they call it multi tasking ?????.
 
I work on mobility scooters I will put the battery’s on test and carry on with the service or other work if I have a lot on.
 
I’ll be onto MG on Monday. I need a car from Monday onwards as I’m driving to Cornwall next Friday for a holiday. The car the MG AA cover provides is only for 2 days as per their policy. MG will need to sort out a courtesy car for Monday onwards.
 
Rob Healy said:
I’ll be onto MG on Monday. I need a car from Monday onwards as I’m driving to Cornwall next Friday for a holiday. The car the MG AA cover provides is only for 2 days as per their policy. MG will need to sort out a courtesy car for Monday onwards.
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Just out of interest you did not stay with the car when the AA was working on the car.
 
But did he stay with them as you can report back the things done, it seems to me that this has happened to a number of car which which seem not to be used every day and not charged often. I use my each day and is recharged each day, again I can relate this to mobility scooters as people do not charge the battery’s until low then come ask why they have to replace them after a year.
 
Over the last year I have mainly driven short distances or the car only got used 2 or 3 times a week. The 12v battery was constantly in red and I even resorted to charging the 12v with a smart charger. After a couple of times of charging the 12v, the smart meter will now say the 12v is full and shut off but when I comes to check the status of the battery it is still in red. The battery is now back to normal after a 4hrs drive down south and another 4hrs drive back home a week later. MG is known to have 12v battery issues. I had that on my previous GS when the car was not driven much. The car needs a very long drive.
 
The car was in my driveway, as the weather was so hot, I was popping in and out but didn’t scrutinise everything the AA bloke did. He was good and seemed to know what he was doing.
 
Hi
just a observation.
i have been off work with Covid and the car has not moved this week i I have just been out to look at the battery’s. The HV is down to 99%and the 12v to 10v so put yhr car into ready for 5 minutes which charged the battery back to 12v.
 
Jto said:
Hi
just a observation.
i have been off work with Covid and the car has not moved this week i I have just been out to look at the battery’s. The HV is down to 99%and the 12v to 10v so put yhr car into ready for 5 minutes which charged the battery back to 12v.
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Sorry to hear you have not feeling great :cry:.
Not a bad idea to put the car in ready mode, to keep the 12volt topped up.
It also helps to get the SOC down on the HV pack, a bit from that 100% mark.
Unavoidable in your present condition, but not good for the HV packs health either, to be sitting there around at 100% max charge, especially in these hot conditions.
If you feel able, take it for a short trip to reduce the range a bit.
 
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